Flexible self-powered integrated sensing system based on a rechargeable zinc-ion battery by using a multifunctional polyacrylamide/carboxymethyl chitosan/LiCl ionic hydrogel

Wearable smart sensors based on conductive hydrogels have attracted intensive research interest due to their high comfort and accurate detection of physiological signals. However, most reported hydrogel sensors cannot work independently and require external power. Herein, we report a novel electrochemical-driving self-powered strain sensor based on a multifunctional polyacrylamide/carboxymethyl chitosan/LiCl (PAAM/CMC/LiCl) hydrogel. This hydrogel was facilely prepared by one-step UV-initiated polymerization strategy and integrated high stretchability (a large strain of 640% with a tensile strength of 67 kPa), anti-drying and anti-freezing (−48.27 °C) properties, self-healing ability, as well as good electrical conductivity (0.56 S/m). As an effective electrolyte material, the PAAM/CMC/LiCl hydrogel is directly assembled with Zn and MnO2 electrodes to form a flexible zinc-ion battery (ZIB), from which a decent specific capacity and desirable stable power output are found even under various mechanical stimuli. Taking advantage of the high strain sensibility of the PAAM/CMC/LiCl hydrogel, a closed loop consisting of the ZIB and a fixed resistor can realize the function of strain sensing and energy storage capabilities simultaneously. This self-powered sensing system has demonstrated high sensitivity, good stability and strong power-generating performance during the real-time monitoring of human activities, which are highly anticipated in the wearable electronics.